docs: def _readASCII(self, filename):
          """ASCII files have no headers. Following synphot, this
          routine will assume the first column is wavelength in Angstroms,
          and the second column is flux in Flam.
  
          """
          self.waveunits = units.Units('angstrom')
          self.fluxunits = units.Units('flam')
          wlist, flist = self._columnsFromASCII(filename)
          self._wavetable = N.array(wlist, dtype=N.float64)
          self._fluxtable = N.array(flist, dtype=N.float64)